opp: Fix return in _opp_add_static_v2()

stable inclusion
from stable-5.10.80
commit 14943891857da24abe5bba4fa132986eb7842713
bugzilla: 185821 https://gitee.com/openeuler/kernel/issues/I4L7CG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=14943891857da24abe5bba4fa132986eb7842713



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[ Upstream commit 27ff8187 ]

Fix sparse warning:
drivers/opp/of.c:924 _opp_add_static_v2() warn: passing zero to 'ERR_PTR'

For duplicate OPPs 'ret' be set to zero.

Fixes: deac8703 ("PM / OPP: _of_add_opp_table_v2(): increment count only if OPP is added")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Acked-by: Weilong Chen <chenweilong@huawei.com>

Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>